help i dont understand this math question
![help i dont understand this math question class=](https://us-static.z-dn.net/files/d66/9be6786fcb313621ba8de8c35d895d60.png)
-------------def-------------
short side: 36
medium side: 45
long side: 72
-------------ghi-------------
short side: 9
medium side: 11.25
long side: 18
-------------jkl-------------
short side: 2.4
medium side: 3
long side: 4.8
all your doing is: scale factor x side = missing length
example: 2x15 = 30
lmk if this helps and brainliest pls :)